With the development of communications technologies, neighboring cells are allowed to use a same frequency in a Universal Mobile Telecommunications System (UMTS, Universal Mobile Telecommunications System), and all users in a same cell receive and transmit signals by using a same frequency. Because all the users receive and transmit signals by using the same frequency, for each user in the UMTS system, inter-cell interference and intra-cell interference may be caused. Therefore, in order to reduce interference to a user, currently, on the premise that a transmission quality requirement of a physical channel is ensured, transmit power of a network side device and transmit power of a user equipment or transmit power of a terminal (UE, User Equipment) are restricted mainly by means of power control.
In the prior art, a base station traces fast fading on an uplink channel, so as to implement inner loop power control. Its implementation principle is as follows: acquiring a signal-to-interference ratio (SIR, Signal-to-Interference Ratio) value of a current uplink channel and comparing the signal-to-interference ratio value with a target SIR value (the target SIR value may be obtained by means of outer loop power control); obtaining a transmit power control command (TPC) of a downlink channel according to a result of the comparing; sending, in each slot, the TPC to a UE through a downlink control channel; and when the UE receives the TPC, adjusting transmit power on the uplink channel in each slot according to the TPC, so as to implement fast power control in an inner loop. For example, an uplink may be a dedicated physical control channel (DPCCH, Didicated Physical Control Channel), an enhanced dedicated physical control channel (E-DPCCH, Enhanced DPCCH), or an enhanced dedicated physical data channel (E-DPDCH Enhanced Dedicated Physical Data Channel). For example, a downlink may be a DPCCH or a fractional-dedicated physical channel (F-DPCH, Fractional-Dedicated Physical Channel).
In traditional Code Division Multiple Access (CDM, Code Division Multiplexing) scheduling, generally multiple users are supported in simultaneously sending data on a DPCCH and a DPDCH/E-DPDCH in one transmission time interval (TTI, Transmission Time Interval), but a near-far effect exists between different UEs. Therefore, a proper overhead of rise over thermal (RoT, Rise over Thermal) that is a ratio between received total wideband power (RTWP, Received Total Wideband Power) and a background noise needs to be allocated to each UE, so that a case in which an uplink channel of another UE cannot be received because one UE occupies extremely high RoT is avoided. Therefore, fast fading of each UE needs to be traced by means of fast power control.
However, the inventor of the present invention finds that, if transmit power of a UE is scheduled based on fixed RoT to trace fast fading, the transmit power of the UE may increase when fast fading is large, which causes relatively strong interference to a neighboring cell; and the transmit power of the UE is relatively small when fast fading is small, which causes weak interference to the neighboring cell. That is, currently, fast power control for an uplink channel cannot well reduce neighboring cell interference.